1. Field of the Invention
The present invention relates to a ladle support tower for a continuous casting plant with two oppositely directed support arms tiltably disposed around a horizontal axis, which ladle supports are provided at the ends of the support arms.
2. Brief Description of the Background of the Invention Including Prior Art
A ladle support tower for a continuous casting plant is known from the German Patent Document DE-B-No. 2,158,902 where the support arms are formed as one leg levers. Each support arm is hinged around a horizontal axis with one end disposed toward a column, and the support arm can be pivoted with a hydraulic pressure cylinder provided at about the middle of the length of the support arm between the hinge axis and the ladle support provided at the other end. Therefore, the hydraulic pressure cylinder has to be capable of lifting up and lowering down a weight of double the weight of the ladle.
In order to avoid the requirement of such overdimensioning of the devices employed two-armed levers have been employed for this purpose. A ladle support tower with support arms provided as two-armed levers of the kind described above is known from European Patent Document EP-B-No. 0017696. The support arms provided at this ladle support tower are furnished with two forked arms providing the work arms, which are joined by a cross-rail, where a power arm starting at the cross-rail protrudes to the middle of the column. The free end of the load arm is supported at a cross-traverse joined at the upper column part by hydraulic cylinders.
This construction is associated with the disadvantage that the cross girder is loaded with a high torque and therefore it has to be constructed torsion-proof. In addition, the power arm can be made only with a very short length which entails that the power arm has to be actuated with a force, which is substantially larger than the force of the weight of the ladles. The hydraulic pressure cylinder used to actuate the power arm therefore has to be overdimensioned. The cross girder connecting the force arms has to be capable of accepting a large bending moment, which results from the loading with the hydraulic pressure cylinder or, respectively, with the weight of the ladle with contents.
It can be considered a further disadvantage of the conventional constructions that the cross-girder requiring larger outer dimensions for this purpose can only with difficulty be pivotably supported in closed bearing provisions. Therefore, the cross girder is supported by bearings at the column, which bearings are open at the top, which is a disadvantage in view of the the rough casting operations. A mounting and demounting of a support arm for repair purposes or for maintenance of the bearing positions is difficult because of the cross-traverse spanning at the top end of the column, since it interferes with the accessibility to the hydraulic pressure cylinders.